Telephone system.



No. 888,427. BATENTED MAY 19, 1908. 0. W. SHARER.

TELEPHONE SYSTEM.

APPLICATION FILED JUNE13,1906.

2 SHEETSSHEET 1.

FICiE INVENTOR:

PATENTED MAY 19, 1908.

G. W. SHARER.

TELEPHONE SYSTEM.

APPLICATION FILED JUNE 13. 1906.

2 SHEETS-SHEET 2.

INVENTORI UNITED STATES PATENT OFFICE.

CARL W. SHARER, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO KEYSTONE TELE- PHONE COMPANY, OF PHILADELPHIA, PENNSYLVANIA, A CORPORATION OF NEW JERSEY.

To all whom it may concern:

Be it known that I, CARL l/V. SHAKER, of Philadelphia, in the county of Philadelphia and State of Pennsylvania, have invented a certain new and useful Improvement in Telephone Systems, whereof the following is a specification, reference being had to the accompanying drawings.

My invention relates to trunk circuits which may be employed between distinct sections of a switch board in the same exchange, or between switch boards in different exchanges.

In operating a circuit of the class contemplated, of the ordinary type employed between diiferent exchanges, here conveniently designated first anc second, the subscriber operator who receives a subscribers call, at the first exchange, necessitating the use of a trunk to the second exchange, establishes communication with the trunk operator at the second exchange by means of the order circuit, and passes the call. Said trunk operator then assigns the trunk to be used and after testing the line of the subscriber called for and finding it not in use, lugs into it with the trunk plug.

IV 1en either the calling or the called subscriber hangs up his receiver, that fact is manifested by a signal local to the subscriber operator at the first exchange, who should then withdraw the plug from the answering jack of the calling subscriber and from the trunk, without delay, as the operator at the second exchange does not receive any indication that the called subscriber has hung up his receiver, until the operator takes down the connection at the first exchange. However, the operator at the first exchange attends to orders to make con nections in preference to taking down connections, and if in the meantime the called subscriber tries to make a call, he closes the circuit through his instrument and a relay, which precludes the closingof the circuit to manifest a signal to the effect that the trunk is disconnected, and consequently the sub scribers line is tied up on the trunk. The disadvantages of this condition, as far as the subscriber is concerned, are two-fold, viz., the subscriber is not only unable to signal the exchange to get a connection, but is Specification of Letters Patent.

Application filed June 13, 1906.

Patented May 19, 1908.

Serial No. 321,424.

reported busy and cannot be called by an other subscriber.

It is the object of my invention to provide means to avoid tying up a subscribers line on a trunk, and as hereinafter described, such means comprises a signaling device, preferably a colored lamp, which is included in the trunk circuit, local to the called subscribers exchange, and manifests to the called subscriber operator when the called subscriber hangs up his receiver, so that said operator may take down the connection and c ear the subscribers line, regardless of whether the trunk is cleared by the calling subscriber operator or not. However, the signal indicating disconnection of the trunk continues to be manifested until the calling subscriber operator clears the trunk.

My invention comprises the various novel features of construction and arrangement hereinafter more definitely specified.

In the accompanying drawings, Figure I, is a diagrammatic view of the calling subscriber operators cord circuit. Fig. II, is a diagrammatic view on an enlarged scale of a trunk circuit between two switchboard sections, or exchanges, embodying my improvement. Fig. III, is a diagrannnatic view of the circuit of the called subscribers line.

In said drawings, the dot and dash line divides the two exchanges; the apparatus to the left thereof and in Fig. I, being comprised in the first exchange 1, and the apparatus to the right thereof and in Fig. III, being comprised in the second exchange 2. The trunk jack 3, is at the first exchange, and 6, is the trunk plug at the second exchange.

If the subscriber operator at the exchange 1, inserts plug 4, in said jack 3, a current will flow from battery 30, through winding of relay 31, (of say 100 ohms resistance) conductor 34, over the sleeve of the plug and jack, and through winding of retardation coil 9 (of say 500 ohms resistance), to grounded side of battery. This operates relay 31, drawing up its armatures 35, and 36, and closes circuit through lamp P2, which is then lighted, and also closes circuit through the windings of relay 7 (of say 15,000 ohms resistance) and relay 33 (of say 100 ohms resistance). The circuit through relays 7, and 33, is from battery 80, through windings of relay 3i, conductor conductor 39, coil 7, conductor 40, coil 41, conductor 42, jack 3, plug 4, conductor 43,

armature 36, conductor 44, relay 33, conductors 45, and 46, to battery 30.

The relay coil 7, draws up its armature 8, thus closing the circuit through the signal lamp 10, which is designated the trunk disconnect lamp. The circuit through this lamp is from battery 19, through conductors 50, 51, 52, 53, lamp 10, armature 8, conductor 55, armature 14, to grounded side of battery. Said lamp 1.0, is preferably red in color and while illuminated notifies the operator at the second exchange that the trunk circuit is connected at the calling-subscribers end of the trunk. Said operator then inserts the trunk plug 6, into jack 5, of the called subscribers line, thereby closing the circuit through the relay coil 12, (of say 100 ohms resistance), and relay coil 28, (of say 100 ohms resistance), drawingup the armatures 13, and 14, thereby opening the circuit of said trunk disconnect lamp 10, and closing the circuit of the ringing lamp 16, and the subscribers disconnect lamp 18. The circuit through relays 12, and 28, is from battery 19, through conductors 50, 56, coil 12, conductors 57, 58, plug 6, jack 5, conductor 59, coil of relay 28, to grounded side of battery. The circuit through the subscribers disconnect lamp 18, is from battery 19, through conductors 50, 60, lamp 18, conductors 61, 62, armature 22, conductors 63, 64, armature 14, (which has been drawn up), to grounded side of battery. The circuit through the ringing lamp 16, is from battery 19, through conductors 50, 51, 52, lamp 1.6, conductor 65, armature 26, conductors 66,64, armature 14, to grounded. side of battery.

The cut-off relay 28, is also operated thereby connecting the called subscribers line onto jack 5. The trunk operator at the ex change 2, then rings for the called subscriber, and when subscriber answers, the circuit is closed through the instrument and back to the operator through the relay coil 20, (of say 100 ohms resistance). The circuit through the relay coil 20, is from battery 19, through conductors 50, 56, coil 12, conductors 57, 58, plug 6, jack 5, called subscribers line, conductor 67, jack 5, plug 6, conductor 68, arma ture 13, conductors 69, 70, coil 20, conductor 71, to battery. The armatures 21, and 22, of said relay coil 20, are thereby drawn up,

' opening the circuit of the subscribers disconnect lamp 18, closing the circuit through the relay coil 25, and closing the short circuit around the winding of the relay coil 7, permitting an increase of current in winding of relay 33, which draws up its armature and opens circuit of lamp 32, thereby notifying the subscriber operator at the exchange 1, that the called subscriber has answered.

25, being drawn up, locks itself by closing the circuit through its own winding, and opens the circuit of the ringing lamp 16, thereby notifying the operator at the exchange 2, that said subscriber has answered.

T/Vhen the conversation is finished and the called subscriber hangs up his receiver, the circuit through the instrument and relay 20, is broken, the relay armatures 21, and 22, drop back to the position indicated in the diagram, thereby closing the circuit of the subscribers disconnect lamp 18, which being illuminated manifests to the operator at the exchange 2, that the called subscriber has hung up his receiver. Moreover, the release of the relay 20, opens the short circuit around the winding of the relay coil 7. This re duces current through winding of relay 33, permitting its armature to drop back and relight lamp 32, and thereby-manifests'to the operator at the exchange 1, that said subscriber has hung up his receiver.

The operators at both exchanges 1 and 2, being simultaneously notified as aforesaid that the called subscriber has hung up his receiver, the subsequent succession of steps in effecting the disconnection of the line is dependent upon which operator first responds to such notification. If, as usual, the operator at the first exchange is engaged in mak ing connections, the operator at the second exchange is the first to respond, and by taking down the connection, opens the circuit through the relay coil 12, permitting its armature 13, and 14, to fall back to the position shown in the diagram, thereby opening the circuit of the relay coil 25, and extinguishing said subscribers disconnect lamp 18, and closing the circuit of the trunk disconnect lamp 10, through contacts local to the armatures of the relay coil 7, and 12, Thereafter, the operator at the exchange 1, removes the plug 4, from the trunk jack 3, thus opening the circuit of the relay coils 7, and 31, permitting armature 8, to stop back to the position shown in the diagram and thereby opening the circuit of the trunk disconnect lamp 10, so that the trunk is ready for another connection. Armatures of relay 31, being released fall back to the positions as shown in the diagram, extinguishing lamp 32. However, the operator at the exchange 1, may first respond to the signal that the called subscriber has hung up his receiver, in whichcase said operator removes the plug 4, from the trunk jack 3, thus opening the circuit of the relay coils 7, and 31, permitting armature 8, to drop back to the position shown in the diagram, thereby closing the circuit of the trunk disconnect lamp 10, through the contacts local to the armatures of the relay coils 12, and 20, releasing armatures of relay 31, which fall back to the positions shown in the diagram and extin Moreover, the armature 26, of the relay coil, guish lamp 32. Thereafter, the operator at the exchange 2, takes doWn the connection, opening the circuit through the relay coil 12, permitting its armatures 13, and 14, to fall back to the position shown in the diagram, thereby opening the circuit of the relay coil 25, and extinguishing the trunk disconnect lamp 10, and the subscribers disconnect lamp 18, so that the trunk is ready for another connection.

It may be observed that both the relay coils 7, and 20, must be deenergized before the circuit of the trunk disconnect lamp 10, is closed. Therefore, if the called subscriber tries to make another call before the operator has cleared the trunk, he closes the circuit through his instrument and relay coil 20, thus preventingthe closing of the circuit of the trunk disconnect lamp 10, and if it were not for the subscribers disconnect lamp 18, the operator at exchange 2, would get no signal, and the called subscribers line would be tied up on the trunk.

The fact that the called subscriber has hung up his receiver being manifested to the operator at exchange 2, by the subscribers disconnect lamp 18, said operator can immediately take down the connection and clear the subscribers line for a new call, regardless of Whether the trunk is cleared or not. However, the trunk disconnect lamp 10, remains lighted, through the contacts local to the relay coils 7, and 12, until the operator at exchange 1, removes the plug from the jack 3, and thereby releases the relay 7, and clears the trunk.

I do not desire to limit myself to the precise details of construction and arrangement described, as Various modifications may be i made therein without departing from the essential features of my invention.

I claim 1. In a telephone trunking system, the combination with trunk and ringing signals; of a supervisory signal in the trunk circuit controlled by the hook contacts of the called subscribers instrument.

2. in a telephone trunking system, the combination of a ringing lamp; a trunk disconnect lamp; and a subseribefs discomiect lamp in the trunk circuit and controlled by the hook contacts of the called subscribefs instrument.

3. In a telephone trunking system, the combination of a ringing lamp and a trunk disconnect lamp local to the called subscribers exchange, a subscribei"s disconnect lamp in the trunk circuit and local to the called subscribe1"s excl'iange, controlled by the hook contacts of the called subscribers instrument.

l. in a telephone trunking system, the combination of a trunk disconnect lamp; a relay for controlling said lamp; a short circuit around said relay; a relay for controlling said short circuit; a ringing lamp and a subscribers disconnect lamp local to the called subscribers exchange and controlled by the hook contacts of the called subscribers instrument.

In testimony whereof, I have hereunto signed my name at Philadelphia, Pennsylvania, this 12th day of June, 1906.

CARL \V. SHAKER. l/Vitnesses ARTHUR E. PAIGE, E. L. FULLERTON. 

